1221999999977 has 2 divisors, whose sum is σ = 1221999999978. Its totient is φ = 1221999999976.

The previous prime is 1221999999967. The next prime is 1222000000003. The reversal of 1221999999977 is 7799999991221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 916645397056 + 305354602921 = 957416^2 + 552589^2 .

It is an emirp because it is prime and its reverse (7799999991221) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221999999977 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1221999999895 and 1221999999904.

It is not a weakly prime, because it can be changed into another prime (1221999999967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610999999988 + 610999999989.

It is an arithmetic number, because the mean of its divisors is an integer number (610999999989).

Almost surely, 2^{1221999999977} is an apocalyptic number.

It is an amenable number.

1221999999977 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221999999977 is an equidigital number, since it uses as much as digits as its factorization.

1221999999977 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 937461924, while the sum is 83.

The spelling of 1221999999977 in words is "one trillion, two hundred twenty-one billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred seventy-seven".